The invention relates to motor-vehicle air-conditioning installations, and more particularly to a method of identifying actuators forming part of these installations.
Motor-vehicle air-conditioning installations comprise a plurality of mixing flaps or air-distribution flaps which are moved by means of actuators typically using stepper motors.
A central control unit addresses commands to the various actuators so as to bring the flaps into positions corresponding to orders received: ventilation, setting of the temperature in the passenger compartment or different areas of the passenger compartment to a desired value, demisting, de-icing, etc. The control unit also receives information transmitted by the actuators, especially information relating to the positions of the flaps, in particular the arrival at the end of opening or closing travel.
The increasing sophistication of air-conditioning installations is conveyed by an increased number of flaps and therefore of actuators. In order to avoid the use of bulky and expensive wiring harnesses, which are awkward to install, it is known to connect the actuators and other peripherals of the air-conditioning installation, such as control panels and temperature probes, to an information bus linked to the control unit and on which travels control information intended for the peripherals and status information transmitted by them to the control unit.
It is then necessary to allocate an individual address to each peripheral, especially to each actuator.
For the sake of standardisation, with a view to reducing costs, actuators of the same type are used for the various flaps. They therefore take the form of similar housings.
When the addresses of the actuators are recorded in them before they are fitted, risks of errors in fitting may arise by reason of the similarities between the housings. It is then desirable to have available an easy and rapid means of verifying the correct fitting, and therefore of identifying the actuators fitted.
The allocation of the addresses may, in a variant, be carried out after fitting of the housings, offering the advantage of standardisation thereof. Here again, this requires a means of identifying the actuators, identification means which should preferably be rapid and automatic.
The same concern for verifying the fitting or the address allocation arises in the event of repair, when one or more actuators have to be replaced.
The object of the invention is to offer a method of identifying an actuator using a stepper motor which makes it possible easily, rapidly and automatically to carry out operations of verification or of address allocation during fitting or repair of an air-conditioning installation.
This object is achieved by virtue of a method comprising the stages which consist in:
causing the flap to move over the whole of its angular range of travel,
counting the number of motor steps during this movement, and
comparing the number of steps counted with at least one item of pre-recorded information corresponding to a particular flap or type of flap.
Thus, the method according to the invention is based on a differentiation between actuators on the basis of the angular ranges of travel of the flaps which they drive. This is because, in an air-conditioning installation, depending on the function which they carry out, the mixing or air-distribution flaps generally have different angular ranges of travel defined by end-of-travel stops.
It would be possible to cause the flap to move several times over the whole of its angular range of travel and then to form an average of the numbers of steps counted during the different movements.
The method according to the invention could be used for checking the fitting of an actuator, during manufacture or repair of the air-conditioning installation. In such a case, the flap associated with this actuator is caused to move, and the conformity between the number of steps counted and the pre-recorded information corresponding to this flap is verified.
Such a check remains useful even in the case in which two different flaps have the same angular range of travel. This can occur, for example, in the case of two flaps having identical functions and situated on the right-hand side and on the left-hand side of the vehicle. The risk of an undetected error on fitting is in effect limited only to a possible inversion between the actuators of the two flaps, this risk even being non-existent if, in the course of a repair, a single actuator of these two flaps has to be replaced.
The method according to the invention could also be used for allocating an address to an actuator, during manufacture or repair of the air-conditioning installation. In such a case, the flap associated with this actuator is caused to move, this flap is identified by comparison between the number of steps counted and several pre-recorded information items corresponding to different flaps, and an address corresponding to the flap identified is stored in a memory of a circuit associated with the actuator.
Upon initial fitting of the actuators in the air-conditioning installation, this address-allocation method is preferably used in the case where the angular ranges of travel of the flaps can be sufficiently differentiated.
Even in the event that two flaps have the same angular range of travel, the address-allocation method nevertheless remains usable in the event of repair, as long as two flap actuators having the same range of travel do not have to be replaced simultaneously.